Picture this: clear, warm water bathing spectacular coral reefs , clouds of fish, circling sharks, and 17 scientists intent on studying the pristine tropical marine ecosystems of the Southern Line Islands . What could go wrong? That these ecosystems are, at best, nearly two days' transit from modern medical facilities—they sit roughly between Hawaii and Tahiti—may not weigh heavily on the minds of our scientists. But as the Diving Safety Officer for the Scripps Institution of Oceanography , I am always aware that even a relatively minor mishap can lead to major problems. Our team is composed...

Not all slugs (snails without shells) are slimy brown pests found in your backyard garden. In the ocean they come in a huge variety of colors — some match the background and are hard to spot, but others are very conspicuous. Nudibranchs in particular are especially popular with divers and underwater photographers because of their often vibrant and beautiful color patterns . The coloration is useful for more than just a pretty photo, however. Bright colors warn predators that these nudibranchs would make a bad meal because they are armed with toxins and other defenses. Where do these defenses...

Stare at a tide pool and you will often see a crust of pink coating the bottom. No, this is not bubblegum from some careless teenager’s shoe: it’s a stony kind of seaweed that, like other seaweeds, harnesses energy from the sun through photosynthesis. It may not look like the kelps and other leafy seaweeds that we usually think of—but seaweeds, which are a type of algae, come in a wide variety of colors, sizes, shapes and textures. These pink stony crusts are found in sunlit parts of the seafloor from the poles to the tropics, and collectively are called crustose coralline algae. Crustose...

Diving can be a wild ride that evokes more than a little trepidation, especially in the Pacific Ocean's famously big, cold waves. Waves that are otherwise fun for my weekend surfing can turn a scientific dive into a serious challenge. But then, diving to support the mission of the Environmental Protection Agency (EPA) can be full of surprises. At a seafloor survey site at the mouth of the Chetco River off the Oregon coast, waves transmit so much energy that divers can feel the swells nearly 80 feet down on the seafloor. As divers swim along the bottom, these swells often push them several...

In recent years, I have taken to watching flying fish along the Maine coast. Not the usual flying fish that skim over tropical seas, but fish dangling from the beaks of flying puffins. Puffins are famous for loading their colorful beaks with a dozen or more fish and winging home to feed their solitary, ravenous chick. In the late 19th century, spotting such overladen beaks was rare, as hunting for food and feathers had depleted most puffin colonies along the Maine coast. Their recovery took 40 years of dedicated conservation work —but the work isn't over. We still need to keep a close eye on...

We all know that hurricanes can have destructive effects on human communities and infrastructure—but what about their effects on coastal wetlands? Until Hurricane Katrina, no one had ever mapped hurricane-caused land loss in Louisiana, where a staggering 90 percent of coastal wetland loss in the United State's contiguous 48 states occurs. The first study to do so, published in 2009, found that the almost back-to-back hurricanes of 2005 (Katrina on Aug. 29 and Rita on Sep. 24) and 2008 (Gustav on Sep. 1 and Ike on Sep. 13) caused an estimated 328 square miles (850 square kilometers) of coastal...

The threat that climate change poses to polar bears has received a lot of attention, but they are not the only Arctic species at risk. Ice-loving seals, such as harp, hooded and ringed seals, are among the many species threatened by climate change. Recent predictions suggest that warming seawater and air will melt 20 percent or more of the Arctic's ice cover in the next 40 years—a scary statistic for the many species in the Arctic that rely on seasonal ice cover for vital activities such as breeding and eating. Harp seals ( Pagophilus groenlandicus ) are a prime example of why sea ice matters...

A lot can happen in five years. Since 2007, the concentration of carbon dioxide in the atmosphere has continued to go up, reaching a concentration of 400 parts per million, and with it Arctic sea ice has continued to melt, reaching a record low in 2012. On a more positive note, more than five million square kilometers of ocean have been designated as shark sanctuaries over the same interval. And just five years ago, the Sant Ocean Hall at the Smithsonian National Museum of Natural History opened. To celebrate its fifth birthday, three new exhibitions that feature the human relationship to the...

Editor's Note: These images and more can be seen at Smithsonian's National Museum of Natural History in Washington, D.C., as a part of the larger exhibit " Portraits of Planet Ocean: The Photography of Brian Skerry " opening on September 17, 2013. Two additional ocean exhibits are also opening: "Fragile Beauty: The Art & Science of Sea Butterflies," which shares the story of how ocean acidification is affecting sea butterflies , and the "Living on an Ocean Planet" gallery, which focuses on the human relationship with the ocean . Their opening coincides with the five-year anniversary of...

This summer, many of you have likely enjoyed feasting on crabs, be they blue, stone, or Dungeness, and a special treat will have been the big, easy morsels of claw meat. The size of this muscle is testament to its role in applying a forceful pinch to prey, predator, or competitor. But many crabs also use their lovely long claws to attract females—a function that does not depend on the power of the pinch. So which of these two uses was more important in driving the claw's evolution: its beauty or its strength? Female fiddler crabs have two small claws that they use to pick up bits of sediment...